1. Field of the Invention
The present invention relates to a material for manufacturing a display panel substrate assembly and a process for manufacturing a display panel substrate assembly. More particularly, the present invention relates to a material for manufacturing a display panel substrate assembly comprising an electrode and a dielectric layer as a substrate constituent element on a glass substrate, such as a front substrate assembly and a rear substrate assembly of a plasma display panel (PDP), and a process for manufacturing a display panel substrate assembly.
2. Description of the Related Art
PDP known as a display panel is a self-emitting type display panel in which a discharge space is formed in the interior by disposing a pair of substrates (usually a glass substrate) opposite to each other at a slight interval, and sealing the surrounding.
Among PDPs, AC-type PDP is provided with an electrode, a dielectric layer for covering the electrode, and a rib having a height of around 100 to 200 μm for partitioning a discharge space.
As an electrode, an Ag electrode obtained by binding an Ag particle with a low melting point glass is mainly used in many cases. Moreover, the dielectric layer and the rib are made of a low melting point glass material.
The conventional process for manufacturing the electrode, the dielectric layer and the rib, a representative of which is described in Japanese Unexamined Patent Application No. 2001-84912 and Japanese Unexamined Patent Application No. 2001-297691, will be explained below.
As a material for forming the electrode (electrode material), a paste obtained by dispersing an Ag fine particle, a low melting point glass powder, a binder resin, and a filler to be mixed if necessary in a solvent, is used.
This electrode material is coated on a glass substrate by a screen-printing method or the like, and the solvent is volatilized by drying, to form an electrode material layer having a predetermined shape. Alternatively, there is a method of forming the electrode material layer by photolithography using a photosensitive resin as the binder resin.
The electrode is prepared by forming the electrode material layer on the glass substrate and, thereafter, heating the glass substrate from room temperature to a softening point of the low melting point glass contained in the material or higher (around 500 to 600° C.) to degrade the binder resin, and soften, melt and sinter the low melting point glass, whereby, Ag particles are bound and Ag and the glass substrate are bound. This step is termed firing. Alternatively, as the electrode material, there is also a material using a superfine particle of Ag. This material can bind an Ag particle itself by heat even when the low melting point glass powder as a binding material is not mixed therein.
After the electrode is formed on the glass substrate, a low melting point glass powder, a binder resin, and a filler to be mixed if necessary are subsequently dispersed in a solvent to obtain a pasty material for forming a dielectric layer (dielectric material), the material is coated on the glass substrate on which the electrode has been disposed, with a screen-printing method or the like, and the solvent is volatilized by drying to form a dielectric material layer.
After formation of the dielectric material layer, the glass substrate is fired from room temperature to a softening point of the low melting point glass contained in the material or higher (around 500 to 600° C.) to degrade the binder resin, and soften and melt the low melting point glass, whereby, the dielectric layer bound to a glass substrate is formed.
For the glass substrate on which the rib need to be formed, a pasty material for forming a rib (rib material) obtained by dispersing a low melting point glass powder, a binder resin, and a filler to be mixed if necessary in a solvent, is coated on the glass substrate on which the electrode and the dielectric layer have been formed, with a screen-printing method or the like, to a desired thickness. Then, the solvent is volatilized from a coated film by drying, to form a plain film. Thereafter, a mask is patterned with a photosensitive resist such as a dry film, and a part other than a dry film mask pattern is cut with a sand blast, whereby, a rib material layer is formed. Then, the dry film mask pattern is removed, and the glass substrate is fired from room temperature to a softening point of the low melting point glass contained in a rib material layer or higher (around 500 to 600° C.) to degrade the binder resin, and soften and melt a low melting point glass, whereby, the rib bound to the glass substrate is formed.
In addition, regarding the aforementioned dielectric layer and rib, there is also a method of filling each material in a transfer intaglio having a groove serving as a negative shape for the rib and the dielectric layer, volatilizing a solvent, and transferring and forming the dielectric layer and the rib on the glass substrate on which the electrode shape has been formed. Also in this case, after formation of material layers for the dielectric and the rib, there is an unchanged step of firing the glass substrate from room temperature to a softening point of the low melting point glass contained in the material or higher (around 500 to 600° C.) to degrade the binder resin, and soften and melt the low melting point glass, whereby the dielectric layer and the rib bound to a glass substrate are formed.
In the aforementioned conventional manufacturing method, it includes a step of coating the material, a step of drying the solvent, and a step of firing every constituent material, which needs for very much time and energy. If after shapes of all constituent materials are formed, all materials can be densified and bound by one time firing (simultaneous firing) in order to improve these points, a time and energy can be greatly saved.
However, in case of trying to perform simultaneous firing by using the conventional materials as they are, the following problems arise.
In a process for firing the material, the binder resin is fired (degraded), and a gas derived from a binder resin need to be discharged to the outside. However, depending on a combination of materials, when the gas derived from the binder resin is discharged to the outside, if degradation of the binder resin for an other material covering the material has not been initiated, or softening of the low melting point glass has been initiated, the gas derived from the binder resin contained in those materials is enclosed in the interior of the material and, finally, a pressure is elevated, and the material is broken in some times.